On this thread, it appears that some people have lost some
serious money (they are not getting much sympathy though):

Reddit

Others are worried that they may not get their drugs:

Reddit

There are worries that users' data could be compromised:

Reddit

Those with orders in transit are worried that the vendors won't
get paid:

Reddit

Some are worried about how they will order illicit supplies now:

Reddit

Others worry about the price of Bitcoin:

Reddit

There's some theories that a Silk Road alternative, Atlantis, may
have been behind the seizure somehow. Atlantis itself, which
billed itself as a "flashier" alternative to SR,
was shut down last month: